mac/gn: Add tests to media_unittests missing in gn build.

media/BUILD.gn

Index: media/BUILD.gn
diff --git a/media/BUILD.gn b/media/BUILD.gn
index ccbb090fc95a32de28cf0a807fd854e73bc3cb41..b703a3806182c653e130fd55ab9cd8cfe6e9ffb1 100644
--- a/media/BUILD.gn
+++ b/media/BUILD.gn
@@ -363,10 +363,6 @@ component("media") {
 
   if (is_mac) {
     public_deps += [ "//media/base/mac" ]
-    libs += [
-      "CoreVideo.framework",
-      "OpenGL.framework",
-    ]
   }
 
   if (is_ios) {
@@ -629,6 +625,9 @@ test("media_unittests") {
       "//ui/android:ui_java",
     ]
   }
+  if (is_mac || is_ios) {
+    deps += [ "//media/base/mac:unittests" ]
+  }
 
   # If ExternalClearKey is built, we can test CdmAdapter.
   if (enable_pepper_cdms) {